ラット網膜色素上皮及びBruch膜の発生過程の電子顕微鏡的観察

Abstract

The development of the retinal pigment epithelum and Bruch's membrane of the albino rat was studied with electron microscope from 14th fetE1 day to 10th postnatal day. The development of the pigment epithelium is classified into the following three stages.(I) Early stage (14th to 18thfetal day). The pigment epithelium is high cuboidal form and in the cytoplasm. there are lage numbers of free ribosomes and a small nunber of rough endoplasmic reticulum.(II) Intermediate stage (19th fetal day to 4th postnatal day). The pigment epithelium has gradually flattened and rough endoplasmic reticulum increased in number and size. Simultaneously, a small number of the smooth endoplasmic reticulum gradually appeared. In the apical cytoplasm, lage number of premelanosomes are developed.(III) Late stage (5th to 10th postnatal day). The cytoplasm is mostly filled with vesicular or tubular smooth endoplasmic reticulum, on the contrary, freeribosomes and rough endoplasmic reticulum relatively dicreased, and premelanosomes began to break down. At the same time, both basal infoldings and microvilli are well formed. At this stage, morphological characteristics of active transport and metaborismus will be performed. The lamellated inclusion body of the pigment epithelium appeared 10th postnatal day, which was just after the formation of rod outersegment.In Bruch's membrane, five layers are identified, which are formed in the following order. The basement membrane of the pigment epithelium was already formed on 14th fetal day. The collagenous layer and the basement membrane of the choriocapillary endothelium began to form on 19th fetal day, bit the later did not become continuous basement membrane until about 4th postnatal day. The elastic lamina on 5th postnatal day, and collagenous layer was dividing into outer and inner portion.The mature structural characteristics of the pigment epithel ium and Bruch's membrane as revealed in this observation were formed 10th postnatal day.